Prefilled Syringe Gasket Circumferential Rubbing for Scratch Removal
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Solution Overview
Problem
Laminated gaskets for prefilled syringes can develop scratches during production, leading to potential leakage of the liquid drug, especially when the scratches align with the gasket's sliding direction.
Innovation Solution
A method involving rubbing the sliding portion of the gasket against a predetermined base in a circumferential direction at a constant speed to reduce surface scratches, ensuring the arithmetic average roughness ratio in the sliding direction to the circumferential direction is not less than 1.00, thereby preventing liquid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gasket is laminated with a fluororesin film to prevent rubber leaching and reduce sliding resistance, then the chemical resistance and slidability are improved, but the film is liable to be scratched during production, leading to potential liquid drug leakage
Solution Approach 1:
The patent applies preliminary action by performing the rubbing step immediately after gasket formation and before final assembly. The sliding portion is rubbed against a predetermined base to remove scratches in the circumferential direction, proactively preventing potential leakage issues before the gasket is installed in the syringe
Solution Approach 2:
The patent converts the harmful effect of scratches into a benefit by using the rubbing process to intentionally create controlled surface modifications. The rubbing against the predetermined base removes harmful scratches while maintaining the necessary surface properties for sealing and sliding functions
2Manufacturing precision
If the sliding portion is rubbed in the circumferential direction to remove scratches, then the scratch resistance is improved, but the surface roughness changes, requiring precise control of the rubbing process
Solution Approach 1:
The patent applies parameter changes by precisely controlling the rubbing process parameters including the rubbing direction (circumferential), rubbing pressure, rubbing speed, and the properties of the predetermined base. These parameter adjustments ensure that scratches are removed while maintaining the arithmetic average roughness ratio within the specified range to preserve sealing performance
Solution Approach 2:
The patent replaces complex multi-directional rubbing mechanisms with a simplified unidirectional circumferential rubbing system. By substituting the rubbing direction constraint and using a predetermined base with specific properties, the process becomes more controllable and easier to implement while achieving the same scratch removal effect
3Reliability
If the arithmetic average roughness ratio R a⊥ /R a// is maintained at not less than 1.00 to ensure sealing performance, then the seal integrity is improved, but the rubbing process parameters must be precisely controlled
Solution Approach 1:
The patent uses parameter changes to control the surface roughness characteristics by adjusting rubbing pressure, rubbing speed, and base material properties. These parameter adjustments ensure the arithmetic average roughness ratio maintains the required relationship (R a⊥ /R a// ≥ 1.00) while keeping the manufacturing process practical and controllable
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively prevents liquid drug leakage by ensuring the gasket's sliding portion remains scratch-free, maintaining the integrity of the seal and enhancing the safety and stability of the prefilled syringe contents.
Implementation Method 1
rubbing a surface of the sliding portion of the formed gasket against a predetermined base
Data Source
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AI summary
The present invention provides a method for producing a prefilled syringe gasket, which ensures that a sliding portion of the gasket (a portion of the gasket to be kept in contact with a syringe barrel) is substantially free from a scratch or an existing scratch of the gasket is substantially eliminated. The prefilled syringe gasket includes a liquid contact portion, and a sliding portion to be kept in contact with an inner surface of a syringe barrel. The method includes the steps of: forming the gasket; and rubbing a surface of the sliding portion of the formed gasket against a predetermined base; wherein a rubbing direction in which the surface of the sliding portion is rubbed in the rubbing step extends circumferentially of the sliding portion.